Got dunk tanked at 12.5% - definitely not 12.5%

Can't see bottom abs (only top 4), have only like 4 veins - all of them in arms, extremely minor definition in quads, only see striations in upper chest/shoulders when I flex with a pump...back and hammies poppin tho. I'm guessing I'm no lower than 15% and probably higher. I did this fasted. What could account for this, I thought dunk tanks were supposed to be accurate, and if not, what is a more accurate method. Reason I need an accurate method is that I'm a weight class athlete and I don't want to cut dangerously low so I need to know when its time to move on up.

by swolegma via Bodybuilding.com Forums - Female Bodybuilding